SIMI VALLEY, Calif. (AP) — Several environmental groups on Tuesday sued state regulators over the cleanup of a former nuclear research lab, saying low-level radioactive waste was improperly shipped to landfills.

Consumer Watchdog, along with other groups, filed a lawsuit Tuesday in Sacramento County Superior Court against the Department of Public Health and Department of Toxic Substances Control, which oversees the cleanup at the Santa Susana Field Laboratory.

Located about 30 miles northwest of Los Angeles, Santa Susana was once home to nuclear research and rocket engine tests. In 1959, one of the reactors suffered a partial nuclear meltdown. Responsible parties including Boeing Co., NASA and the U.S Energy Department have been working with state officials to meet a 2017 deadline to rid the nearly 2,900-acre site of contaminated soil.

In their complaint, the groups contend that materials from several buildings that were demolished were sent to landfills and metal recycling shops that are not licensed to accept radioactive waste. They also sought a temporary restraining order to stop Boeing from tearing down a plutonium fuel fabrication building on the hilltop complex.

"It is paramount that the public be protected from toxic, and in this instance radioactive, harm," Liza Tucker of Consumer Watchdog said in a statement.

Officials at the toxic control agency rejected the allegations, saying that debris sent offsite posed no threat to human health or the environment.

Stewart Black, a deputy director at DTSC, said the state followed the rules in the demolishing and disposal of old buildings.

During the Cold War, workers at the site tested thousands of rockets and experimented with nuclear reactors, which were operational until 1980. And by the time the rest of the lab closed in 2006, a toxic legacy of radioactive and chemical contamination had been left.

Former workers and residents in nearby neighborhoods have blamed the lab for a variety of health problems.